What’s up with Walker?

May was a great month for the Seattle Mariners, accentuated by a 16-4 thumping of the San Diego Padres. By wRC+, the Mariners were the second-best hitting team in baseball for the month trailing only the Boston Red Sox. Robinson Cano and Kyle Seager were red hot, Leonys Martin was excellent before hitting the disabled list, and even Adam Lind appeared to have gotten things going. Ironically enough, it could be argued that the offense has been carrying the pitching staff.

One member of the pitching staff, who had an outstanding start to the season, found himself on the other end of things for May: Taijuan Walker.

Let’s talk about the good stuff first. Walker was downright dominant in April and in terms of fWAR, he was the M’s best pitcher. Across four starts and 25 innings pitched he posted a 1.44 ERA and a 2.12 FIP. His 9.00 strikeouts per nine and 1.08 walks per nine were also excellent with a single home run surrendered in his first start against Oakland. Also included in April was a dazzling seven-inning, 11-strikeout performance against the Houston Astros in which Walker’s fastball registered at 98.3 miles per hour.

April was a glimpse not into the future, but into what the scouting reports of year’s past said about Walker: there’s ace potential. Over the winter Prospect Insider’s Luke Arkins discussed how the right-hander could find himself atop the Mariners rotation as soon as this season with a breakout year. Waking up on May 1st, this certainly looked like it would be the case.

Now let’s talk about the bad stuff. Walker made six starts in May and in five was credited with the loss. In 29 and 1/3 innings pitched he posted a 4.91 ERA and a 6.43 FIP. The strikeout rate dropped some to 7.67 per nine, but the walk rate jumped up to 2.45 per nine and, perhaps most noticeably, the home run rate spiked to 2.76 per nine innings.

Walker gave up at least one home run in five of those six starts including a three-spot allowed to the Minnesota Twins for a total of nine long balls. The 23-year-old’s allowance of the home run is likely the most problematic aspect of the month of May, but that’s far from a worse case scenario.

Some of the home run spike can be considered fluky as a 22.5 percent home run per fly ball rate is nearly double what would be considered major league average. Walker’s career home run rate sits at 12.7 percent so the overall 2016 mark of 17.9 percent is above what we’d expect to see. The good news? All it takes is a couple homer-free starts to get that rate down to a more normal level. The question then, is how that is how to make that happen.

For the month of May, Walker increase his fastball usage of 64.0 percent of all pitches thrown compared to 52.5 percent usage in April. The right-hander did post his highest average fastball velocity mark since early 2015. Considering the success he was having with the pitch early on, the game plan may have changed to include more of the heat. The additional use of the four-seam fastball came at the expense of the splitter, which Walker threw less often in May compared to April. He also used his curveball a little less in May as well.

Splitters are notorious for inducing ground balls and weak contact. Walker’s decrease in splitter usage from April to May coincides with a decrease in ground ball percentage from April to May. Now, it’s not entirely accurate to bridge these two gaps together and assume this is the answer. But, we can use these facts to help paint a picture.

Part of the reason Walker’s ground ball rate declined is because his home run rate went up. Part of the reason for the increase home run rate has to do with the increase in hard contact opposing hitters put up against the right-hander in May compared to April. In fact, the two go hand-in-hand; the harder you hit the ball, all other factors aside, the better chance you have of hitting a home run. That much is relative common sense.

The switch from the splitter to the four-seam likely has something to do with the 1.143 slugging percentage hitters put up on his splitter for the month of May. If the pitch isn’t working, it only makes sense that it would be thrown less, and when the fastball is working, it makes sense to throw it more. Walker did manage an 11.8 percent whiff rate on his fastball for May, an increase compared to April.

Could it be that opposing hitters are sitting on the fastball, knowing that they are going to see it? Walker perhaps having some slight command issues, as indicated by the increase in walk rate, could suggest he’s looking to the fastball in an effort to get back in counts. The splitter not getting outs doesn’t help his case, either. There’s an adage that 98 miles per hour is less difficult to hit when you know it’s coming.

The answer to Walker’s May struggles could be as simple as making an adjustment with his pitch selection. Hitters have obviously made the adjustment as shown in the May results, it will be up to him to return the favor. A few more cutters and splitters along with the curveball will certainly keep hitters off balance for when the heat comes.

There’s no reason to postpone the former top prospect’s breakout season yet. His season ERA of 3.31 still looks good and represents the success and struggles he’s had on the year. His xFIP of 3.72 tells us that with a normalized home run rate, his 4.45 FIP would look a lot better.

The 23-year-old is still sitting on stardom, and with the team having the success it has had, some of the pressure of Walker performing likely has been alleviated. With the focus on the offense, and prolific come backs, the spotlight shines less on the right-hander’s struggles, which can be a very good thing for a young pitcher.

It still looks like this could be the year for Taijuan to take that next big step, and when he takes the mound on Friday night, it will be a new month. May is officially in the rear view mirror, and for Walker, good riddance.